A nanorod is a nano-sized structure having a diameter in the range of several tens of nanometers to several hundreds of nanometers and a large aspect ratio, and a device employing the nanorod is used in various fields such as a field effect transistor (FET), a field emission device (FED), a light emitting diode (LED), a solar cell, a gas sensor, a chemical sensor, a biosensor, and the like according to applications.
A synthesis of the nanorod may be broadly divided into two methods: a vapor method using a vapor-liquid-solid (VLS) mechanism employing a metal catalyst and a liquid method using a solution.
The vapor method is a method such that a state of a material is changed into a gaseous state using high heat, and atoms in the gaseous state condense to synthesize nanorods of various shapes. The vapor method makes it difficult to control sizes and properties of nanorods and to uniformly arrange the synthesized nanorods.
Further, a crystal structure and an optical characteristic of a nanorod, which is produced by the liquid method, are poor due to a large number of defects, as compared to the nanorod synthesized by the vapor method, and similar to the vapor method, there is a problem in that arrangement and formation of electrodes are difficult.
Conventional methods of producing a nanorod include chemical polymerization, electrochemical polymerization, chemical vapor deposition (CVD), and carbothermal reduction, but the conventional methods have many restrictions which require a high synthesis temperature, a reaction time, expensive vacuum equipment, the use of a harmful gas, and the like in order to obtain a high-quality nanorod.
Further, a surface crack may occur in a conventional process of separating a nanorod from a substrate, and damage and thermal damage may be caused by strong heat energy and heat transfer.